4.10 or 4.30?
#75357
06/18/08 02:16 AM
06/18/08 02:16 AM
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Joined: Aug 2004
Posts: 1,213 Los Angeles, CA
Mobarge
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pro stock
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OP
pro stock
Joined: Aug 2004
Posts: 1,213
Los Angeles, CA
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I'm about two steps away from having the car finished (for now - you know how it is), and one of those steps is a gear swap in my 8 3/4.
Right now, I'm running 3.23 Sure Grip in a 489 case (freshly rebuilt, green bearings, axles, etc.) - which I know are completely the wrong gears for my setup.
I've got a 413 that is putting out about 450 - 475 to the crank. Power is going thru a built 727 Torqueflite with a 9.5 inch California Converter by Art Carr TC. Stall is around 3,800 RPM.
You can see that makes for an interesting combination with the 3.23s! It just won't lock up (which goes without saying). Fortunately, the thing has never heated up or been flogged.
I need the gears to make the combo - so my thought is going with either a 4.10 or 4.30 ratio. Car is for the street. Very little highway driving. Occasional blast down the 1/8 mile.
Any thoughts on the gears to get here guys and gals?
'71 SSP - SOLD!
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Re: 4.10 or 4.30?
[Re: Mobarge]
#75358
06/18/08 02:28 AM
06/18/08 02:28 AM
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Joined: Dec 2003
Posts: 5,314 Carstairs, Alberta, Canada
dave571
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master
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Carstairs, Alberta, Canada
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Tire size will be your deciding factor. Anything less than 30", and i think the 4.30's are a bit steep. FWIW, I had 4.30's in my car, and switched them down to 410's. Liked them, but made highway time a little crappy. Since then, I've gone one more step down to 3.73's I would think you are better to narrow the choices to 410's or 391's, but that's my .
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Re: 4.10 or 4.30?
[Re: Mobarge]
#75359
06/18/08 02:32 AM
06/18/08 02:32 AM
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Joined: Aug 2005
Posts: 4,861 Riverside, Ca
R70RUNNER
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master
Joined: Aug 2005
Posts: 4,861
Riverside, Ca
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how tall are your tires? 4.30's are a lot of gear with less then 30" tall tires on the street Back when I used to drive around on 4.10's with a 28" tall tire not too bad.
Current cars: 2000 Dak Quad Cab, 2012 Challenger,1970 Road Runner, 1994 Firehawk
1966 Coronet post sedan, 1988 Corvette, 2005 Magnum RT all SOLD
R70RUNNER<---VP Inland Empire Chapter of the MPM
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Re: 4.10 or 4.30?
[Re: Mobarge]
#75360
06/18/08 11:40 AM
06/18/08 11:40 AM
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Joined: Jan 2003
Posts: 4,712 Moved to N.E. Tennessee
GomangoCuda
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master
Joined: Jan 2003
Posts: 4,712
Moved to N.E. Tennessee
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Keep in mind that there is approximately a 5% difference between 4.10 and 4.30 gears. For examle: If you would cruise at 3000 rpm with the 4.10's, with the 4.30's you would go the same speed at 3150 rpm. Big woop. You'll barely notice the difference. For the usage you described I would probably get the 4.30's and use a 28" tire.
Last edited by GomangoCuda; 06/18/08 11:45 AM.
In theory, there is no difference between theory and practice. In practice, there is.
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Re: 4.10 or 4.30?
[Re: gch]
#75366
06/18/08 10:25 PM
06/18/08 10:25 PM
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Joined: Aug 2004
Posts: 1,213 Los Angeles, CA
Mobarge
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pro stock
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OP
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Posts: 1,213
Los Angeles, CA
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I believe the RPM range on the cam is 1,500 to 7,500 if I'm not mistaken.
'71 SSP - SOLD!
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Re: 4.10 or 4.30?
[Re: Mobarge]
#75367
06/19/08 12:35 AM
06/19/08 12:35 AM
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Anonymous
Unregistered
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Anonymous
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1500-7500 usable rpm? i think not. more then likely if its a true 7500rpm camshaft, there will be nothing under 3000rpm.
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Re: 4.10 or 4.30?
#75368
06/19/08 01:00 AM
06/19/08 01:00 AM
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Joined: Aug 2004
Posts: 1,213 Los Angeles, CA
Mobarge
OP
pro stock
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OP
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Joined: Aug 2004
Posts: 1,213
Los Angeles, CA
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Like I said, I could be wrong! I got home and dug out my cam specs (it has been a few years since I looked). Here you go: Melling Performance 440 (#23302 WG-1031) Cam Lift (int/exh) .320/.320 Valve Lift (int/exh) .480/.480 SAE Duration (int/exh) 302/302 SAE Timing: BTC = 43; ABC = 79;BBC = 79; ATC = 43 Lobe Center (int/exh) 108/108 Lash Hot (int/exh) HYD/HYD .050 Duration (int/exh) 236/236 .050 Timing BTC = 10; ABC = 46; BBC = 46; ATC = 10
'71 SSP - SOLD!
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Re: 4.10 or 4.30?
[Re: Mobarge]
#75369
06/19/08 01:03 AM
06/19/08 01:03 AM
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Anonymous
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Anonymous
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melling eh? anyways.. 4.10 or 4.30's won't make a difference IMO.
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